This invention relates generally to laser surgery, and more particularly to materials and endotracheal tubes useful in such surgery.
Tracheal tubes are used during surgical procedures to provide ventilation and anesthesia for the patient. The distal ends of these tubes are inserted into the lower portions of the trachea and have a balloon disposed at the distal end which may be inflated from outside the patient through an auxiliary lumen, so as to provide an effective leak resistant seal between the tube and the trachea. Such tubes, however, in the case of laser surgery of the throat, present certain difficulties. For example, materials such as polyvinyl chloride (PVC) that are normally used to make endotracheal tubes absorb infrared energy from the laser if the laser beam happens to strike the tube. As a result, the laser can in effect burn a hole through the tube with potentially serious consequences for the patient. Not only does the tube convey high concentrations of oxygen, but in many cases the gas flowing through the main lumen of the endotracheal tube may be another highly flammable gas. A hole burned through the tube wall exposing the oxygen or flammable anesthestic gas can cause ignition of the tube while in the patient's trachea with obvious catastrophic results.
Of course a material that would resist penetration by a laser beam could find additional uses for shielding during laser surgery on other parts of the body.
As a result of the disadvantages mentioned above, endotracheal tubes have previously been protected by a helical winding of a strip of material such as aluminum which reflects the infrared energy of the laser. This protects the tube, but is believed to drastically affect the safety and flexibility of the tube. Endotracheal tubes have also been made of metal. However, this results in rigid tubes which traumatize the patient's respiratory tract. In addition, laser beams can reflect off the metallic surface of such a tube onto healthy tissues, which results in unnecessary trauma to the patient.
Other tubes, such as that shown in U.S. Pat. No. 4,378,796, have been proposed to address these disadvantages. The tube of the '796 patent includes a dispersion of finely divided metallic powder such as aluminum, silver, or gold which allegedly absorb and reflect energy received from the impact of the laser beam. It is stated to be advantageous if the whole of the endotracheal tube comprises such a metallic dispersion, so that its resistance to the infrared energy of the laser beam is improved. An example of such a tube is given in the '796 patent in which the tube itself is of silicone containing 1% by weight aluminum powder.
An endotracheal tube made of an oxide of a metal for the same purpose is described in U.S. Pat. No. 4,375,811.
During laser surgery, particularly in the area of the trachea, the space above the balloon of the endotracheal tube can become filled with smoke due to the action of the laser on the tissues. This, of course, complicates the surgeon's job. The aforementioned U.S. Pat. No. 4,378,796 attempts to address this problem by providing an auxiliary lumen with an opening on the side of the endotracheal tube proximal to the balloon through which lumen an inert gas, such as nitrogen, is passed to sweep the smoke out of the upper part of the trachea.